This invention relates to a circuit which can be made in module form for providing interfacing circuitry between low power level control signal generating circuits and electrical loads and particularly for interfacing between such loads and control signal generating circuits which are particularly noise sensitive.
Tremendous strides have been made in recent years devising new integrated semiconductor circuits which can be arranged to generate control signals for use in initiating and terminating the energization of various electrical loads. However, such circuits provide only low power level control signals so many electrical loads cannot be operated directly by the lower power level control signals making it necessary to provide interfacing circuits responsive to the low power level control signals to provide the necessary connection of the electrical loads to an appropriate power source.
If an interfacing circuit is to be usable in the design of various industrial control circuits which use integrated semiconductor circuits such as timers, counters, sequences and the like, it is essential that the interfacing circuit provide noise signal protection for such integrated semiconductor circuitry. Noise signals, such as may be due to radio frequency generated signals, if of sufficient duration and magnitude and impressed on some integrated semiconductor circuits, can cause false indications and/or damage the semiconductor circuits.